1) Field of the Invention
The present invention relates to a process for producing an amino composition by an addition reaction between a polyamine and an alkenyl group-containing compound. The amino composition obtained by the process according to the present invention has reactivity with epoxy resins, isocyanates and the like, and is useful as curing agents for epoxy resins or chain extenders for polyurethane resins.
2) Related Art
An amino composition obtained by the addition reaction of a polyamine with an alkenyl group-containing compound is known to be characterized in that it has low viscosity and its content of unreacted polyamine is relatively low. For instance, an epoxy resin composition which contains curing agents for epoxy resins comprising said amino composition provides an excellent property of an epoxy resin cured product. Therefore, said amino composition has an excellent industrial availability.
The process for producing the above-mentioned amino composition comprising the step of addition reaction between a polyamine and an alkenyl group-containing compound in the presence of a strongly basic catalyst has been publicly known (Japanese Patent Kokai No. 2002-161076).
According to the process directed in Japanese Patent Kokai No. 2002-161076, the addition reaction is conducted by firstly contacting a polyamine with catalysts and then an alkenyl group-containing compound is added immediately after increasing the temperature of the reaction mixture.
In this case, the point of termination of the addition reaction is determined by measuring the content of unreacted alkenyl group-containing compounds in the reaction mixture. Namely, when the content of unreacted alkenyl group-containing compounds becomes under a certain amount, the addition reaction is regarded to be completed.
More specifically, the reaction time is determined so that the content of unreacted alkenyl group-containing compounds becomes not more than 1% by weight.
However, the above-mentioned process has some defects. For example, it often takes long time until the reaction is completed. More specifically, it takes more than 30 minutes from the finish of supplying an alkenyl group-containing compound up to the time that the content of unreacted alkenyl group-containing compounds becomes not more than 1% by weight.
Further, the reaction time often varies widely. Moreover, the content of unreacted alkenyl group-containing compounds sometimes becomes difficult to be under 1% by weight and the reaction is not completed.
Extension of the reaction time causes some defects such as the formation of an unfavorable polymer of alkenyl group-containing compounds as a by-product.
The formation of a polymer of alkenyl group-containing compounds and/or the presence of residual unreacted alkenyl group-containing compounds cause the lack of stability in properties of the obtainable amino composition.